Influence of radioactivity on surface interaction forces

Although some differences have been observed, the transport behavior of radioactive aerosol particles has often been assumed to be analogous to the behavior of nonradioactive aerosols in dispersion models. However, radioactive particles can become electrostatically charged as a result of the decay process. Theories have been proposed to describe this self-charging phenomenon, which may have a significant effect on how these particles interact with one another and with charged surfaces in the environment. In this study, atomic force microscopy (AFM) was employed to quantify surface forces between a particle and a planar surface and to compare measurements with and without the involvement of radioactivity. The main objective of this work is to assess directly the effects of radioactivity on the surface interactions of radioactive aerosols via the measurement of the adhesion force. The adhesion force between a silicon nitride AFM tip and an activated gold substrate was measured so that any possible effects due to radioactivity could be observed. The adhesion force between the tip and the gold surface increased significantly when the gold substrate (25 mm2 surface area) was activated to a level of approximately 0.6 mCi. The results of this investigation will prompt further work into the effects of radioactivity in particle–surface interactions.

Radioactivity-induced surface charging.Figure optionsDownload high-quality image (85 K)Download as PowerPoint slideResearch highlights
► Different types of radioactivity cause ionization in the surrounding environment
► Ions generated by radioactive decay are adsorbed onto surfaces leading to surface charging
► Atomic force microscopy is used to capture the influence of radioactivity on surface forces
► Radioactivity-induced surface charging may be used to explain the behavior of radioactive particle plumes